Through board stacking of multiple lga-connected components

ABSTRACT

A package design is provided where a chip module is connected to a printed circuit board (PCB) via a land grid array (LGA) on the top surface of the PCB, and where a power supply is connected to the PCB via a second LGA on the bottom surface of the PCB. The stack of the chip module, power supply, and LGA is held in place and compressed with actuation hardware forming an adjustable frame. The package allows field replacibility of either the module, or the PS, and provides the shortest possible wiring distance from the PS to the module leading to higher performance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/511,815, filed Aug. 29, 2006.

This invention was made with Government support under Contract No.:NBCH3039004 (DARPA) awarded by Defense, Advanced Research ProjectsAgency. The Government has certain rights in this invention.

BACKGROUND

This invention relates to a package where a chip module is connected toa printed circuit board (PCB) via a land grid array (LGA), and moreparticularly, the package includes the LGA on a top surface of the PCBand a power supply connected to the PCB via a second LGA on the bottomsurface of the PCB.

One type of surface-mount packaging used for integrated circuits (IC) ispin grid array (PGA). In PGA pins are used to conduct electrical signalsfrom the integrated circuit to a printed circuit board (PCB) the IC isplaced on. Another type of surface-mount packaging used for integratedcircuits is ball grid array (BGA). Using BGA, connector pins arereplaced by balls of solder joined to the bottom of the package. Adevice is placed on a PCB that carries copper pads in a pattern thatmatches the solder balls. Repair to the components of the chip module iscompleted by shipping the PCB and soldered module to a repair facilitywhich is expensive and time consuming.

A land grid array (LGA) is a physical interface for some microprocessorspackage families. Unlike the pin grid array (PGA) interface found onmost available processors, there are no pins on the chip module for LGA.Instead, on the LGA, is a separate, interposed structure consisting ofan array of conducting compliant contacts which touch the conductivepads on the bottom of the chip module and also touch the pads on themotherboard.

Land Grid Array (LGA) interposers are typically used to reversiblyconnect a chip module to a printed circuit board (PCB). This brings bothsignal and power from the PCB to and from the module. Power suppliesserving the module are usually located on the PCB as close to the moduleas possible to minimize the wiring distance and the associated resistivelosses and time delays. However, the minimal distance possible where apower supply is immediately adjacent to the module still limits thecloseness to an extent equal to or greater than the width of the powersupply for at least some fraction of wiring paths.

Chip packages experience time delays and higher power usage resultingfrom the distance between the power supply and the module. Currentpackages attempt to mitigate the delay time resulting from the distancebetween the power supply and the module by having small decouplingcapacitors (decaps) soldered on the printed wiring board, and as closeto the module as possible to store as much energy from the power supply.Thus, when the chip calls for power, the power comes from the capacitorfirst rather than having to go all the way out to a power supply.

Moreover, in conventional electronic packaging designs utilizing BGAconnections, repair to chip modules is conducted off-line, e.g. at arepair facility which requires extra cost in terms of shipping, timedelays, etc.

It would therefore be desirable for a chip module to be capable of beingrepaired in the field. It would also be desirable for components of achip module to be individually removable for repair. It would further bedesirable to minimize wiring distances between components and a powersupply in a module package.

BRIEF SUMMARY

In an aspect of the present invention a chip module package or systemfor use with an electronic device comprises a first land grid array(LGA) positioned between and coupled to a chip module and a first sideof a first printed circuit board (PCB). A second LGA is positionedbetween and coupled to a power supply and a second side of the firstPCB. The second LGA has connections for electrically coupling the powersupply to the PCB. An adjustable support frame is adapted tocompressively support the first LGA, the PCB, the second LGA, and thepower supply as a stack of components.

In a related aspect of the invention, a cooling component is positionedabove the chip module, and the package may include multiple printedcircuit boards in which one of the multiple printed circuit boards mayinclude capacitors.

In a related aspect of the invention, the package may further includemultiple electrical components.

In a related aspect of the invention the chip module package is used ina computer system.

In a related aspect of the invention, the second LGA is positionedbetween a power supply and a bottom surface of the PCB, and the firstLGA is positioned between the chip module and a top surface of the PCB,and a cooling component is positioned above the chip module.

In a related aspect of the invention, the support frame is a single loadspring system.

In another related aspect of the invention, the adjustable support frameincludes a series of elements coupled together to form a perimeter aboutthe chip module package. A plurality of first slidable elementsinterrelate with a plurality of substantially perpendicular secondelements, and a resilient member interacts with an adjustable member.The resilient member is coupled to end portions of the first elementssuch that when the adjustable member is moved in a specified direction,the resilient member is adapted to urge the first slidable elements tomove the second elements toward each other providing compression of thechip module package.

In another related aspect of the invention, the adjustable support frameincludes a top support plate and bottom support plate for supporting thestack of components therebetween. Support posts for engaging the top andbottom support plates maintain separation thereof, and enable movementof the support plates relative to the other support plate. A means foradjusting the support posts is provided to hold the top support plateand bottom support plate in compression.

In a related aspect of the invention, the adjustable support frameincludes a series of elements coupled together to form a perimeter aboutthe chip module. A plurality of top first slidable elements are coupledto a top second element and a first LGA housing structure, and aplurality of bottom first slidable elements are coupled to a bottomsecond element and a second LGA housing structure. End portions of thetop first elements are coupled to a top resilient element whichinteracts with a top adjustable member, and end portions of the bottomfirst elements are coupled to a bottom resilient element which interactswith a bottom adjustable member. The top and bottom resilient membersare adapted to move using the top and bottom adjustable members suchthat the top and bottom first slidable elements urge the top and bottomsecond elements independently toward each other providing separate topand bottom compression of the chip module package.

In a further aspect of the invention a chip module package or system foruse with a computer system comprises a first LGA positioned between andcoupled to a chip module and a top surface of a first printed circuitboard (PCB). A power supply component is positioned between and coupledto a second LGA and a bottom side of the PCB. A cooling component ispositioned above the chip module, and an adjustable support frame isadapted to couple together the first LGA, the PCB, and the second LGA,the power supply and the cooling component, thereby coupling togetherthe chip module package.

In another aspect of the invention a method of packaging a chip modulefor use with a computer system comprises providing a chip module, afirst LGA and a second LGA, providing a power supply component,providing a cooling component, and providing an adjustable supportframe. The first LGA is positioned between and coupled to a chip moduleand a top surface of a first printed circuit board (PCB). The second LGAis positioned between and coupled to the power supply and a bottom sideof the PCB. The cooling component is positioned above the chip module.The adjustable support frame is adapted to selectively couple togetherthe chip module, the first and second LGAs, the PCB, and the powersupply and the cooling component. The adjustable support frame is closedto compress the chip module, the first and second LGAs, the PCB, thepower supply and the cooling component into a complete chip modulepackage as one embodiment of the present invention.

In another aspect of the invention, a chip module kit for use with acomputer system comprises a first LGA positioned between and coupled toa chip module and a top surface of a first printed circuit board (PCB).A power supply component is positioned between and coupled to a secondLGA and a bottom side of the PCB. A cooling component is positionedabove the chip module, and an adjustable support frame is adapted tocouple together the first LGA, the PCB, and the second LGA, the powersupply and the cooling component.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

These and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptionof illustrative embodiments thereof, which is to be read in connectionwith the accompanying drawings, in which:

FIG. 1 is a front elevational view of a chip module package in an openposition showing a printed circuit board (PCB) in cross-section, chipmodule, cooler, power supply, two LGA connectors, and a support frame.

FIG. 2 is a front elevational view of a chip module package similar tothe module shown in FIG. 1 including a circuit board includingcapacitors;

FIG. 3 is a front elevational view of the chip module package shown inFIG. 2 in a closed position; and

FIG. 4 is a front elevational view of an open chip module packageshowing a printed circuit board (PCB) in cross-section, and whereindependent frames are positioned above and below the PCB.

DETAILED DESCRIPTION

The present invention provides a chip module package/system or a kitwhich provides multiple components surrounded by an adjustable framewhich compressibly holds the components together while allowing fordetaching the components after the frame is opened. Referring to FIG. 1,the present invention includes the placement of a power supply 70 on thebottom side of a printed circuit board (PCB) 50, preferably in theshadow of a integrated circuit (IC) or chip module 20. The PCB includesconducting vias extending from the bottom to the top of the PCB 50. Thisallows power connections to be only one PCB board thickness away fromthe module bottom. Further, the power supply located on the PCB bottomcould be connected to the PCB by means of a land grid array (LGA), thusenabling the field replacibility of the power supply which is prone tofield failure. An upper LGA 30 is above the PCB 50 and the lower LGA 60is positioned below the PCB 50, as shown in FIG. 1. The upper LGA 30 andlower LGA 60 include annular pads or connectors 35 providing conductingpathways between the PCB and the module and between the PCB and powersupply to the LGAs when the module package is compressed into a closedposition. The module is held together by the constant pressure of aframe 12 when the frame 12 is in the closed position.

Referring to FIG. 1, the upper LGA 30 includes annular pads orconnectors 35, which have, for example, one millimeter distance betweenthe center of a connector 35 and the center of the next connector 35.The lower LGA 60 includes connectors 35, which have, for example, onequarter of the quantity of the connectors for the upper LGA 30. Theupper and lower LGAs 30, 60, respectively, receive voltage and signalsthrough the connectors 35. The lower LGA 60 only receives voltage, soless connectors 35 are needed to spread the power evenly. The design andconstituent materials of the upper and lower LGA contacts may differ,e.g., a power LGA may have a larger diameter and be made of differentconducting metals.

In one aspect, this invention (as shown in FIG. 1) entails a packagedesign or packaging system including a stack of components 14 where achip module 20 is connected to a PCB 50 via an LGA on the top surface ofthe PCB 50, and where a power supply 70 is connected to the PCB vialower LGA 60 communicating with the bottom surface of the PCB 50. Thestack of components 14 includes, in the example shown in FIG. 1, thecooler 100, the module 20, an upper LGA 30, PCB 50, lower LGA 60, andpower supply (PS) 70 is held in place with actuation hardware, e.g., theframe 12 (shown in FIG. 1). The frame 12 is adjustable and allows forfield replacibility of either the chip module 20 or the PS 70 andprovides the shortest possible wiring distance from the PS 70 to thechip module 20 leading to highest performance.

The frame 12 or actuation hardware could be either a single load springsystem holding the entire stack of components 14 together (as shown inFIG. 1), or two separate spring systems connected to a centraladjustable frame (as shown in FIG. 4) to allow independent replacementof either the chip module 20 or the power supply 70 upon field failureor upgrade requirements.

Referring to FIG. 1, a first embodiment of a chip module package 10comprises, a stack of components 14 including the cooler 100, chipmodule 20, upper LGA 30, PCB 50, lower LGA 60, and power supply 70 heldtogether with a single spring system or frame 12, and may also bereferred to as the “clamshell design”. In this design the total force oneach LGA should be equal. This may be accomplished using the same numberof contacts of the same type. Alternatively, different numbers ofcontacts for each LGA may be used, where the force per contact would beunequal.

Referring again to FIG. 1, the chip module package 10 comprises theframe 12 which includes a stiffener plate 204 a at the top of the moduleand a stiffener plate 204 b at the bottom of the module package 10connected by slidable posts 208 a and 208 b. The posts 208 a and 208 bconnect to a resilient spring plate 212 at the bottom of the modulepackage 10. Four posts may be implemented to hold the module package 10with two posts 208 a and 208 b being visible in FIG. 1. The coupling ofthe posts, stiffener plate, and spring plate result in the frame 12about the module components. A water cooler 100 is positioned above thechip module. Thereby, the water cooler 100 is positioned as part of anupper part of the component stack 14 where the upper part of thecomponent stack is defined as all components above the PCB 50, and thelower part of the component stack 14 is defined as all components belowthe PCB 50. In this embodiment, the inlet and outlet water ports 104 aand 104 b of the water cooler 100 are accommodated by protruding eitherthrough the stiffener/loadplate 204 a or exit laterally to avoidinterference with the load plate and would exit between two load posts,e.g., 208 a and 208 b. Other cooling devices may be used, for example,cooling devices using fins, or other liquid circulating cooling devices.

A screw 210 is attached to the spring plate 212 by a threaded connectionpresses against into the stiffener plate 204 b when screwed toward it.When the screw 210 is adjusted in one direction, the ends of the springplate 212 are pulled downwardly in concert with the screw. Thereby, theends of the spring plate 212 connected to the bottom ends 209 b and 207b of the slidable posts 208 a, 208 b move downwardly, and the top ends209 a and 207 a of the slidable posts 208 a and 208 b at the top of themodule pull the components in the module closer together.

Referring again to FIG. 1, a power supply 70 is positioned beneath thelower LGA 60 and above the stiffener plate 204 b. The power supply 70 isconnected to the PCB 50 via the lower LGA 60. Thus, an embodiment of theunique electronic module package 10 according to the invention is shownin FIG. 1, whereby the surrounding actuating hardware comprise a frame12 defining the perimeter of the module package 10, i.e., the springplate 212, the posts 208 a, 208 b, and the stiffener plates 204 a, 204b, hold together both the module 20 and the power supply 70 each withtheir respective land grid arrays 30, 60. The posts 208 a, 208 b andstiffener plates 204 a, 204 b are slidably coupled and substantiallyperpendicular to each other. FIG. 1 also shows an optional cooler in thecompressed stack.

An advantage of the present module package 10 results from combining theupper LGA 30 with the water cooler 100 and the chip module 20 sandwichedbetween to make a comparably thin package and eliminate the need forfins used for cooling. Another advantage of the invention is that thecomponents are field replaceable. For example, the power supply 70and/or the chip module 20 are field replaceable. Since both of thecomponents are field replaceable, an engineer can replace the componentsin the field, e.g., replacing either the power supply or replacing thechip module or both. In PGA and BGA type surface-mount packaging usedfor integrated circuits, the pins or balls are used to conductelectrical signals from the integrated circuit to a printed circuitboard (PCB) it is placed on. However, if the components are not heldtogether by land grid array technology, repair to the chip module iscompleted by shipping the module to a repair facility. Thus, the systemaccording to the present invention allows repair in the field of thechip module.

Referring again to FIG. 1, the embodiment of the present inventionpositions a power supply 70 underneath the module 20 using a land gridarray connect 60. Further, the present invention includes amicro-channel cooler 100, i.e., a water cooler, positioned above thechip 20. The power supply 70 and the water cooler 100 can be part of thechip module package 10 individually or in combination as in theembodiment show in FIG. 1. Also, the module package 10 or componentstack 14 may include multiple chips (not shown).

Referring to FIG. 2, another embodiment of a module package 300 includesa component stack 214 similar to the component stack 14 of theembodiment shown in FIG. 1, however, a PCB 302 is positioned above thepower supply 70 in addition to the PCB 50 shown in module package 10,such that the PCB 302 is positioned between the lower LGA 60 and thepower supply 70. The PCB 302 is advantageously positioned in the modulepackage 300 by holding other circuitry operable in conjunction with thepower supply, such as resistors and capacitors. Thus, module package 300provides more processing and packaging capabilities.

FIG. 3 depicts the module package 300 shown in FIG. 2 in a closedposition wherein the components between the stiffener plates 204 a and204 b are compressed. The screw 210 is extended to result in the springplate 212 being extended downwardly to draw the ends 207 a and 209 a ofthe slidable posts 208 a, 208 b and the stiffener plate 204 a towardsthe opposing stiffener plate 204 b to hold the package 300 incompression.

Referring to FIG. 4, another embodiment of a module package of thepresent invention is shown which includes a first set of fixed posts 404and 408 attached at ends 404 a and 408 a, respectively, to a top springplate 212 a and pass through the stiffener plate 204 a. Further, theposts 404 and 408 are attached at ends 404 b and 408 b to the PCB via astructure 30 a at least partially housing the upper LGA 30. A second setof fixed posts 412 and 416 are connected at respective ends 412 a and416 a to a structure 60 a attached ridgidly to PCB at least partiallyhousing the lower LGA 60, and are attached to the bottom spring plate212 b at respective ends 412 b and 416 b after passing through thestiffener plate 204 b. The posts 404, 408, 412, and 416 avoid the module20 and power supply 70.

The package 400 shown in FIG. 4 differs from the packages 10 and 300shown in FIGS. 1 and 2 because the posts are divided to separate thestack compression of the top side and its components from the stackcomponents of the bottom side and its components instead of passingthrough the PCB 50 as in module packages 300 and 10. Further, the PCB 50is compressed between the upper and lower LGAs 30, 60, respectively, bythe ends 404 b and 412 a on one side, and by 408 b and 416 a on theother side of the package. Thus, separate and independent upper andlower frames 12 a, 12 b, respectively, are formed over and under the PCB50, where the upper frame 12 a comprising posts 404, 408, stiffenerplate 204 a and top spring plate 212 a compress the stack of components440 a comprising the water cooler 100, chip module 20, and upper LGA 30.The lower frame 12 b comprising posts 412, 416, stiffener plate 204 band bottom spring plate 212 b compress the stack of components 440 bcomprising the PS 70 and the lower LGA 60. The components above andbeneath the PCB can thereby be compressed independently from one anotherusing the screws 210 a and 210 b, as described in embodiment 10, toadjust the compression of the package. An advantage of this package 400in addition to the independent compression, is that only one side of thepackage need be opened to service a component. For example, if acomponent on the bottom of the package needs to be removed, then onlythe bottom of the package needs to be opened.

Positioning the power supply 70 under the module 20 advantageouslydecreases the distance between the power supply and the module, thusincreasing power supply performance. Further, the time delay betweenwhen the module calls for power and when the power is received by themodule 20 is less because of the decreased proximity of the power supplyto the module 20. It is more advantageous to have the power supply closeto the module to minimize the need for capacitors which require valuablereal estate on the module.

Another embodiment of the present invention implements a heat spreaderwith fins instead of the water cooler 100 for each of the embodimentsdepicted in FIGS. 1-4. The fins are typically pieces of metal thatproject at right angles from a hot surface and act to draw away the heatand present a large surface area for air to remove the heat. A typicalair heat sink consists of a block of conducting metal (e.g., aluminum orcopper) that sits on the hot surface (e.g., the chip) and which has suchfins attached at right angles. Alternatively, a heat sink can be made bytaking a block of metal and machining a series of deep grooves into it,thus defining fins without the need to attach fins by methods such assoldering or welding.

In another embodiment according to the present invention the bottom of afin heat spreader can act as the load plate for the top module LGA 30 byembedding load posts into the metal either as blind tapped holes orthrough holes with bolts on the top fin surface.

In another embodiment according to the present invention, the powersupply will itself have fins for heat dissipation. In such a case,either a rigid frame or plate may be built between the power supply andthe PCB 50 to accommodate the load bearing posts 208 a and 208 b, shownin FIGS. 1-3, or a rigid metal plate sleeve that would go over the fins(the fins passing through slots), extend laterally beyond the powersupply and provide a means of attaching load posts and a spring system.

Other embodiments according to the present invention include utilizinghybrid LGA/BGA/s instead of the LGAs. A hybrid LGA, by itself, is knowngenerally in the art and includes a compliant connector on one side ofan insulating carrier and a BGA solder connection on the other side. Thesolder connection side would usually, but not necessarily, be solderedto the PCB. The compliant sides would extend outward from the PCB tomake contact with a chip module or a power supply mating surface.However, any combination of BGA or compliant connectors could be used.Dual hybrid stack embodiments may include, for example, BGA to moduleand BGA to power supply, or BGA to board from both top and bottom, orBGA to module and bottom of board, or BGA to PS and top of board.

While the present invention has been particularly shown and describedwith respect to preferred embodiments thereof, it will be understood bythose skilled in the art that changes in forms and details may be madewithout departing from the spirit and scope of the present application.It is therefore intended that the present invention not be limited tothe exact forms and details described and illustrated herein, but fallswithin the scope of the appended claims.

1. A chip module package or system for use with an electronic device,which comprises: a first land grid array (LGA) positioned between andcoupled to a chip module and a first side of a first printed circuitboard (PCB); a second LGA positioned between and coupled to a powersupply and a second side of the first PCB, the second LGA havingconnections for electrically coupling the power supply to the first PCB;an adjustable support frame adapted to compressively support the firstLGA, the first PCB, the second LGA, and the power supply as a stack ofcomponents; and a plurality of additional printed circuit boardselectrically communicating with the first PCB.
 2. The package of claim1, wherein at least one of the additional printed circuit boardsincludes capacitors.
 3. The package of claim 1, wherein the second LGAis positioned between a power supply and a bottom surface of the firstPCB, and the first LGA is positioned between the chip module and a topsurface of the first PCB, and a cooling component is positioned abovethe chip module.
 4. The package of claim 3, wherein the coolingcomponent is liquid cooled.
 5. The package of claim 1, wherein theadjustable support frame includes a series of elements coupled togetherto form a perimeter about the chip module, and a plurality of top firstslidable elements are coupled to a top second element and a first LGAhousing structure, and a plurality of bottom first slidable elements arecoupled to a bottom second element and a second LGA housing structure,and end portions of the top first elements are coupled to a topresilient element which interacts with a top adjustable member, and endportions of the bottom first elements are coupled to a bottom resilientelement which interacts with a bottom adjustable member, whereby the topand bottom resilient members are adapted to move using the top andbottom adjustable members such that the top and bottom first slidableelements urge the top and bottom second elements independently towardeach other providing separate top and bottom compression of the chipmodule package.
 6. A chip module package or system for use with anelectronic device, which comprises: a first LGA positioned between andcoupled to a chip module and a top surface of a first printed circuitboard (PCB); a power supply component positioned between and coupled toa second LGA and a bottom side of the PCB; a cooling componentpositioned above the chip module; and an adjustable support frameadapted to couple together the first LGA, the PCB, and the second LGA,the power supply and the cooling component, thereby coupling togetherthe chip module package.
 7. The package of claim 6, wherein the chipmodule package is used in a computer system.
 8. The package of claim 6,wherein the adjustable support frame includes a series of elementscoupled together to form a perimeter about the chip module, and fourfirst slidable elements interrelate with four substantiallyperpendicular second elements, a resilient member interacts with anadjustable member and the resilient member being coupled to end portionsof the first elements such that when the adjustable member is moved in aspecified direction, the resilient member is adapted to urge the firstslidable elements to move the second elements toward each otherproviding compression of the chip module package.
 9. The package ofclaim 6, wherein the adjustable support frame includes a top supportplate and bottom support plate for supporting the stack of componentstherebetween; support posts for engaging the top and bottom supportplates and maintaining separation thereof and enabling movement of thesupport plates relative to the other support plate; and means foradjusting the support posts to hold the top support plate and bottomsupport plate in compression.
 10. The package of claim 6, wherein theadjustable support frame includes four top first slidable elementscoupled to a top second element and a first LGA frame, and four bottomfirst slidable elements coupled to a bottom second element and a secondLGA frame, and end portions of the top first elements being coupled to atop resilient element which interacts with a top adjustable member, andend portions of the four bottom first elements being coupled to a bottomresilient element which interacts with a bottom adjustable member,whereby the top and bottom resilient members are adjusted using the topand bottom adjustable members and are adapted to move the top and bottomfirst slidable elements to urge the top and bottom second elementsindependently toward each other providing separate top and bottomcompression of the chip module package.
 11. A method of packaging a chipmodule for use with a computer system comprising: providing a chipmodule; providing a first LGA and a second LGA; providing a power supplycomponent; providing a cooling component; providing an adjustablesupport frame; positioning the first LGA between and coupled to a chipmodule and a top surface of a first printed circuit board (PCB);positioning the second LGA between and coupled to the power supply and abottom side of the first PCB; positioning the cooling component abovethe chip module; adapting the adjustable support frame to selectivelycouple together the chip module, the first and second LGAs, the firstPCB, the power supply and the cooling component; and closing theadjustable support frame to compress the chip module, the first andsecond LGAs, the first PCB, the power supply and the cooling componentinto a chip module package.
 12. A chip module kit for use with anelectronic device, which comprises: a first LGA positioned between andcoupled to a chip module and a top surface of a first printed circuitboard (PCB); a power supply component positioned between and coupled toa second LGA and a bottom side of the first PCB; a cooling componentpositioned above the chip module; and an adjustable support frameadapted to couple together the first LGA, the first PCB, and the secondLGA, the power supply and the cooling component.